Closed-cycle thermodynamic engine for generating electrical energy from solar energy and associated method of operation

ABSTRACT

The present disclosure provides systems and methods for collecting and converting solar energy into electrical energy by using solar collectors with closed-cycle thermodynamic engines. The solar collectors are configured to collect solar energy and to distribute the collected solar energy in a pulsating manner directly into closed-cycle thermodynamic engines, piezoelectric generators, and the like. The pulsating manner means that the solar energy is allowed to enter into a particular engine or generator periodically, for a predetermined period of time, similar to turning a switch ON and OFF. The closed-cycle thermodynamic engines utilize a reciprocating piston to generate energy based on thermal expansion of a working fluid based on concentrated solar energy.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present non-provisional patent application is a continuation-in-partof co-pending U.S. patent application Ser. No. 12/212,249, filed Sep.17, 2008, and entitled “SYSTEMS AND METHODS FOR COLLECTING SOLAR ENERGYFOR CONVERSION TO ELECTRICAL ENERGY,” and co-pending U.S. patentapplication Ser. No. 12/212,408, filed Sep. 17, 2008, and entitled“APPARATUS FOR COLLECTING SOLAR ENERGY FOR CONVERSION TO ELECTRICALENERGY,” each of which claims priority to U.S. Provisional PatentApplication Ser. No. 60/993,946, filed Sep. 17, 2007, entitled “METHODAND APPARATUS FOR CONVERTING SOLAR ENERGY INTO ELECTRICAL ENERGY,” allof which are incorporated in full by reference herein. The presentnon-provisional patent application is also a continuation-in-part ofco-pending U.S. patent application Ser. No. 12/355,390, filed Jan. 16,2009, and entitled “SYSTEMS AND METHODS FOR COLLECTING SOLAR ENERGY FORCONVERSION TO ELECTRICAL ENERGY WITH PIEZOELECTRIC GENERATORS” whichclaims priority to U.S. Provisional Patent Application Ser. No.61/011,298, filed Jan. 16, 2008, entitled “METHOD AND APPARATUS FORCONVERTING SOLAR ENERGY INTO ELECTRICAL ENERGY USING CLOSED-CYCLETHERMODYNAMIC ENGINES AND PIEZO-ELECTRIC GENERATORS,” all of which areincorporated in full by reference herein. The present non-provisionalpatent application is also a continuation-in-part of co-pending U.S.patent application Ser. No. 12/365,753, filed Feb. 4, 2009, entitled“SYSTEMS AND METHODS FOR COLLECTING SOLAR ENERGY FOR ENGINES ANDPIEZOELECTRIC GENERATORS” which claims priority to U.S. ProvisionalPatent Application Ser. No. 61/063,508, filed Feb. 4, 2008, entitled“METHOD AND APPARATUS FOR CONVERTING SOLAR ENERGY INTO ELECTRICAL ENERGYUSING MULTIPLE CLOSED-CYCLE THERMODYNAMIC ENGINE AND PIEZO-ELECTRICGENERATORS,” all of which are incorporated in full by reference herein.Additionally, the present non-provisional patent application claimspriority to U.S. Provisional Patent Application Ser. No. 61/066,371,filed Feb. 20, 2008, entitled “METHOD AND APPARATUS FOR CONVERTINGELECTROMAGNETIC ENERGY INTO ELECTRIC AND THERMAL ENERGY USING ACLOSED-CYCLE THERMODYNAMIC ENGINE AND ELECTRIC GENERATOR,” which isincorporated in full by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to solar-to-electrical energyconversion. More particularly, the present invention provides systemsand methods for a closed-cycle thermodynamic engine that generateselectrical energy through a reciprocating piston operated by thermalexpansion based on concentrated solar energy.

BACKGROUND OF THE INVENTION

Solar energy is one of the renewable energy sources that does notpollute, it is free, and available virtually everywhere in the world.For these reasons, over the years there have been many systems andmethods that attempted to utilize solar energy and convert it into otherusable forms of energy such as electricity. More recently, due toperceived shortages and higher prices of fossil fuels and due topollution concerns, the interest has increased and the pace ofdevelopment of technologies that utilize alternative energy sources(such as solar) has accelerated.

There are two main techniques developed to harvest solar energy. Thefirst technique utilizes photovoltaic solar cells to directly convertsolar energy into electricity. The photovoltaic solar cells have theadvantage of small size, but are expensive to manufacture and the priceper watt has leveled due to the high cost of the semiconductor substrateutilized to construct the photovoltaic solar cells. There are many typesof designs and materials used to make photovoltaic solar cells whichaffect their cost and conversion efficiency. Current commerciallyavailable solar cells typically reach a starting efficiency around 18%which drops over time. The cells produce direct current (DC) that needsto be regulated, and for higher power applications typically the DCcurrent also needs to be converted to AC current.

The second technique utilizes the heat (infrared radiation) associatedwith the solar energy. Assuming that the goal is to generate electricalenergy, the solar radiation gets collected, concentrated, and utilizedas a heat source for various systems that convert the heat intomechanical energy, which is then converted into electrical energy.Successful machines developed to convert heat into mechanical energy canbe based on thermodynamic cycles. Mechanical energy produced by thesemachines is further converted into electrical energy by using rotatinggenerators or linear generators. For example, in the case of a Stirlingengine, heat (which can come from any heat source) is applied at one endof the engine and cooling is provided at a different location. Theworking fluid (gas), which is sealed inside the engine, goes through acycle of heating (expansion) and cooling (contraction). The cycle forcesa piston inside the engine to move and produce mechanical energy. Whenthe heat source is solar, successful engine designs use an intermediatemedium such as molten salt to more uniformly distribute the heat aroundthe outside surface of the heating end of the engine.

With respect to the second technique, problems arise when the surface ofthe engine is exposed to large temperature gradients due to closeproximity of the heat and cooling sources on the surface of the engine.For example, conventional engines can see extreme temperatures from dayto night and along the length of the engine body with temperaturesranging from over 1000 degrees Fahrenheit to room temperature across theengine body. Disadvantageously, these types of engines face difficultmaterial problems such as weld joint cracking and loss of materialproperties due to thermal cycling over time. Also, there are lossesassociated with heat radiation from the hot end of these types ofengines leading to inefficiency.

Piezoelectricity is the ability of some materials (notably crystals andcertain ceramics) to generate an electric potential in response toapplied mechanical stress. This can take the form of a separation ofelectric charge across the crystal lattice. If the material is notshort-circuited, the applied charge induces a voltage across thematerial. Direct piezoelectricity of some substances like quartz cangenerate potential differences of thousands of volts.

BRIEF SUMMARY OF THE INVENTION

In an exemplary embodiment, the present invention provides aclosed-cycle thermodynamic engine including an engine body; a first heatchamber and a second heat chamber at opposite ends of the engine body; asolar collection apparatus connected to the first heat chamber and thesecond heat chamber and configured to distribute collected solar energyinto each of the first heat chamber and the second heat chamber for apredetermined time period; a piston slidingly disposed within the enginebody between the first heat chamber and the second heat chamber; and anelectrical generation device configured to generate electricity basedupon reciprocation of the piston. The closed-cycle thermodynamic enginefurther includes a heat absorber in each of the first heat chamber andthe second heat chamber; wherein the heat absorber operable to absorbthe collected solar energy and to release heat into a working fluid ineach of the first heat chamber and the second heat chamber. Theclosed-cycle thermodynamic engine optionally further includes one ormore fiber optic links between the first heat chamber and the secondheat chamber; wherein the one or more fiber optic links are operable toexchange heat between the first heat chamber and the second heat chamberto thereby assist in a cooling cycle. The closed-cycle thermodynamicengine can further include a heat exchanger coupled to the engine body;wherein the heat exchange is operable to cool each of the first heatchamber and the second heat chamber in the cooling cycle. The enginebody can include a sealed cylindrical shape including the first heatchamber and the second heat chamber at opposite ends of the sealedcylindrical shape; and wherein the sealed cylindrical shape includesoptically transparent ends at opposite ends of the sealed cylindricalshape operable to allow concentrated solar energy to enter the firstheat chamber and the second heat chamber. The optically transparent endsand the piston include a material essentially transparent to visible andinfra-red (IR) radiation. The closed-cycle thermodynamic engine furtherincludes one or more magnets disposed to the piston; and one or morecoils disposed to an interior of the engine body; wherein reciprocationof the piston thereby causes the one or more magnets to generate avoltage in the one or more coils. The one or more magnets includeelectro-magnets with variable magnetic strength adjusted responsive toan amount of collected solar energy. The closed-cycle thermodynamicengine alternatively further includes a mechanism disposed to the pistonoperable to convert reciprocal motion of the piston to rotationalmotion; a shaft disposed to the mechanism; and an external electricgenerator disposed to the shaft. The closed-cycle thermodynamic engineoptionally further includes a mechanism disposed to the piston operableto convert reciprocal motion of the piston to rotational motion; ainterior shaft disposed to the mechanism; an interior magnet disposed tothe shaft; an exterior magnet outside of the engine body in proximity ofthe interior magnet and operable to rotate responsive to rotation of theinterior magnet; and an external electric generator disposed to anexterior shaft disposed to the exterior magnet. The closed-cyclethermodynamic engine further includes a pulsation algorithm operable tocontrol the solar collection apparatus to control the predetermined timeperiod.

In another exemplary embodiment, a method of operating a closed-cyclethermodynamic engine includes distributing collected solar energy in afirst chamber for a first time period; reciprocating a piston responsiveto expansion of a first working fluid in the first chamber; cooling offthe first chamber while distributing the collected solar energy in asecond chamber for a second time period; reciprocating the pistonresponsive to expansion of a second working fluid in the second chamber;and generating electrical energy during the reciprocating steps. Themethod further includes cooling off the second chamber whiledistributing the collected solar energy in the first chamber for thesecond time period; and repeating the method. The method furtherincludes utilizing a heat absorber in the first chamber and the secondchamber to absorb the collected solar energy and to release heat into aworking fluid in each of the first chamber and the second chamber. Themethod optionally further includes utilizing one or more fiber opticlinks between the first chamber and the second chamber to exchange heatbetween the first chamber and the second chamber to thereby assist in acooling cycle. The method alternatively further includes utilizing aheat exchanger to cool each of the first chamber and the second chamberin the cooling cycle. The method can include adjusting anelectro-magnetic magnet strength responsive to the amount of collectedsolar energy. The method further includes adjusting a pulsationalgorithm to control the first time period and the second time period.

In a further exemplary embodiment, a closed-cycle thermodynamic engineapparatus includes an engine body; a first chamber and a second chamberat opposite ends of the engine body; a solar collection apparatusconnected to the first chamber and the second chamber and configured todistribute collected solar energy into each of the first chamber and thesecond chamber for a predetermined time period; a piston slidinglydisposed within the engine body between the first chamber and the secondchamber; an electrical generation device configured to generateelectricity based upon reciprocation of the piston; and a controllercoupled to the first chamber, the second chamber, the solar collectionapparatus, and the electrical generation device, wherein the controlleris configured to control pulsation of the collected solar energy intoeach of the first chamber and the second chamber. The solar collectionapparatus is coupled to the engine body in a manner to avoid excessiveheating of the engine body and the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated and described herein with referenceto the various drawings, in which like reference numbers denote likesystem components and/or method steps, respectively, and in which:

FIG. 1 is system schematic including a dual-surface reflector forcollecting and concentrating solar energy according to an exemplaryembodiment of the present invention;

FIG. 2 are multiple low-profile solar collectors for providing a flatterand compact low-profile arrangement according to an exemplary embodimentof the present invention;

FIG. 3 is a mechanism for combining solar radiation from multiplelow-profile solar collectors through light guides according to anexemplary embodiment of the present invention;

FIG. 4 is a diagram of various designs for a focusing/collimatingelement according to an exemplary embodiment of the present invention;

FIGS. 5A and 5B are partial cross-sectional views of a piezoelectricgenerator according to an exemplary embodiment of the present invention;

FIGS. 6A and 6B are partial cross-sectional views of a thermodynamicclosed-cycle based engine according to an exemplary embodiment of thepresent invention;

FIG. 7 is a diagram of an energy distribution and delivery system forconcentrated solar energy directly into thermodynamic closed-cycle basedengines and/or piezoelectric generators according to an exemplaryembodiment of the present invention;

FIGS. 8 and 9 are diagrams of a solar array utilizing optical switchesand reflective surfaces with the solar collectors of FIG. 2 according toan exemplary embodiment of the present invention;

FIGS. 10 and 11 are diagrams of a solar array utilizing optical switchesand reflective surfaces with the dual-surface reflector of FIG. 1according to an exemplary embodiment of the present invention;

FIGS. 12-15 are diagrams of solar arrays utilizing the distributionmechanism of FIG. 3 with the solar collectors of FIG. 2 and thedual-surface reflector of FIG. 1 according to an exemplary embodiment ofthe present invention;

FIG. 16 is a flowchart of an energy distribution and delivery mechanismfor concentrating and releasing solar energy in a pulsating mannerdirectly into multiple systems according to an exemplary embodiment ofthe present invention;

FIG. 17 is a flowchart of a mechanism to convert solar energy intoelectric energy according to an exemplary embodiment of the presentinvention;

FIG. 18 is a block diagram of a controller for controlling the pulsatingmanner of solar energy distribution according to an exemplary embodimentof the present invention;

FIGS. 19A and 19B are diagrams of a closed-cycle thermodynamic enginewith an integrated electric generator according to an exemplaryembodiment of the present invention;

FIGS. 20A and 20B are diagrams of a closed-cycle thermodynamic enginewith an external electric generator according to an exemplary embodimentof the present invention; and

FIG. 21 is a flowchart of engine operation of the closed-cyclethermodynamic engines of FIGS. 19 and 20.

DETAILED DESCRIPTION OF THE INVENTION

In various exemplary embodiments, the present invention provides systemsand methods for collecting and converting solar energy into electricalenergy by using solar collectors with closed-cycle thermodynamicengines. The solar collectors are configured to collect solar energy andto distribute the collected solar energy in a pulsating manner directlyinto closed-cycle thermodynamic engines, piezoelectric generators, andthe like. The pulsating manner means that the solar energy is allowed toenter into a particular engine or generator periodically, for apredetermined period of time, similar to turning a switch ON and OFF.Advantageously, this enables more efficient use of the collected solarenergy.

The present invention includes solar collectors that concentrate solarenergy and mechanisms for transporting and transferring the concentratedsolar energy directly into multiple engines and/or generators withoutheating the outside surface of the engines and/or generators.Additionally, the present invention includes mechanisms to direct solarenergy into each of the multiple engines and/or generators to increaseoverall system efficiency by maximizing the use of collected solarenergy. Advantageously, the delivery system of the present inventionavoids heating an outside surface of the multiple engines and/orgenerators as is done in conventional designs, provides a closed designto protect the collectors, and maximizes efficiency through multipleengines and/or generators and optical splitters.

Referring to FIG. 1, a dual-surface reflector 100 is illustrated forcollecting and concentrating solar energy 102 according to an exemplaryembodiment of the present invention. The dual-surfaces on thedual-surface reflector 100 include a primary reflector 104 and asecondary reflector 106. The reflectors 104, 106 can be in a parabolicshape, a spherical shape, and the like. Also, the secondary reflector106 can be concave or convex depending on the positioning of thesecondary reflector 106 relative to the primary reflector 104. Theprimary reflector 104 is pointed towards the solar energy 102, and thesecondary reflector 106 is located above the primary reflector 104. Theprimary reflector 104 is configured to reflect the solar energy 102 tothe secondary reflector 106 which in turn concentrates the solar energy102 through an opening 108 at a center of the primary reflector 104.

An outer perimeter support ring 110 is disposed around the edges of theprimary reflector 104 to maintain the shape of the primary reflector 104and to anchor in place the primary reflector 104. A transparent andflexible material 112 connects to the primary reflector 104 and to thesupport ring 110 to hold the secondary reflector 106 in place. Thetransparent and flexible material 112 is configured to allow the solarenergy 102 to pass through, and can be constructed from a material thatis optically transparent in the infrared region, such as a material inthe Teflon® family of products, for example, fluorinated ethylenepropylene (FEP) or the like. The transparent and flexible material 112provides a closed design of the dual-surface reflector 100.Advantageously, the transparent and flexible material 112 can seal thedual-surface reflector 100 from the elements, i.e. wind, airborneparticles, dirt, bird droppings, etc. This prevents deterioration of thereflectors 104, 106 and reduces maintenance with respect to cleaning thereflectors 104, 106.

A support member 114 can be disposed to the outer perimeter support ring110 and a base 116. The base 116 can connect to a tracking mechanism 118through a rotatable member 120. The tracking mechanism 118 is configuredto continuously point the reflectors 104, 106 towards the sun byinitiating a rotation of the rotatable member 120 to rotate the base116, the support member 114 and the support ring 110. For example, thetracking mechanism 118 can include a microcontroller or the like canrotate according to location (e.g., an integrated Global PositioningSatellite (GPS) receiver, preprogrammed location, or the like), date,and time or the like. Additionally, the tracking mechanism 118 caninclude feedback from sensors that detect the position of the sun.

The base 116 can include one or more motors and electric generators 122,124. The opening 108 is connected to the base 116 to provideconcentrated solar energy from the reflectors 104, 106 to the one ormore motors and electric generators 122, 124. For a single motor andelectric generator 122, the motor and electric generator 122 ispositioned to allow the concentrated solar energy to enter working fluid(e.g., a liquid, a gas, or a phase change substance) without heating anoutside surface of the single motor and electric generator 122. The oneor more motors and electric generators 122, 124 can includepiezoelectric generators, closed-cycle thermodynamic engines, orvariations of these.

FIG. 1 illustrates an exemplary embodiment with two of the motors andelectric generators 122, 124. This exemplary embodiment includes anoptical switch 126 and reflecting surfaces 128 to direct theconcentrated solar energy into each of the motors and electricgenerators 122, 124. Those of ordinary skill in the art will recognizethat the base 116 can include more than two of the motors and electricgenerators 122, 124 with a corresponding optical switch 126 andreflecting surfaces 128 to concentrate solar energy into each of themore than two of the motors and electric generators 122, 124. Theoptical switch 126 is configured to provide concentrated solar energyfor predetermined intervals into each of the motors and electricgenerators 122, 124.

Advantageously, the optical switch 126 enables the dual-surfacereflector 100 to input energy into each of the motors and electricgenerators 122, 124 in a pulsating manner only when needed and for aduration of time that is completely controllable. This enables thedual-surface reflector 100 to avoid wasting collected solar energy, i.e.the optical switch 126 enables the collected energy to be used in eachof the motors and electric generators 122, 124 as needed. For example,the optical switch 126 can be configured to direct collected solarenergy into a heating chamber of each of the motors and electricgenerators 122, 124 only during a heating cycle. The motors and electricgenerators 122, 124 each have offset heating cycles to allow allcollected solar energy to be used, i.e. the optical switch 126 cyclesbetween each of the motors and electric generators 122, 124 for theirindividual heating cycles.

In an exemplary embodiment, the dual-surface reflector 100 can includeinflatable components, such as an inflatable portion 130 between theprimary reflector 104 and the secondary reflector 106 and in the outerperimeter support ring 110. Air lines 132, 134 can be connected to theinflatable portion 130 and the outer perimeter support ring 110,respectively, to allow inflation through a valve 136, a pressure monitor138, and an air pump 140. Additionally, a microcontroller 142 can beoperably connected to the air pump 140, the pressure monitor 138, thevalve 136, the tracking mechanism 118, etc. The microcontroller 142 canprovide various control and monitoring functions of the dual-surfacereflector 100.

Collectively, the components 136, 138, 140, 142 can be located withinthe base 116, attached to the base 116, in the tracking mechanism 118,external to the base 116 and the tracking mechanism 118, etc. The valve136 can include multiple valves, such as, for example, an OFF valve, anON/OFF line 132/134 valve, an OFF/ON ON/OFF line 132/134 valve, and soon for additional lines as needed, or the valve 136 can include multipleindividual ON/OFF valves controlled by the microcontroller 142.

The inflatable components can be deflated and stored, such as in acompartment of the base 114. For example, the inflatable componentscould be stored in inclement weather, high winds, and the like toprotect the inflatable components from damage. The microcontroller 142can be connected to sensors which provide various feedback regardingcurrent conditions, such as wind speed and the like. The microcontroller142 can be configured to automatically deflate the inflatable componentsresponsive to high winds, for example.

The support member 114 and the outer perimeter support ring 110,collectively, are configured to maintain the desired shape of theprimary reflector 104, the secondary reflector 106, and the transparentand flexible material 112. The pressure monitor 138 is configured toprovide feedback to the microcontroller 142 about the air pressure inthe inflatable portion 130 and the outer perimeter support ring 110. Thedual-surface reflector 100 can also include controllable relief pressurevalves (not shown) to enable the release of air to deflate thedual-surface reflector 100. The transparent and flexible material 112can form a closed space 130 which is inflated through the air line 132to provide a shape of the secondary reflector 106, i.e. air is includedin the interior of the dual-surface reflector 100 formed by thetransparent and flexible material 112, the secondary reflector 106 andthe primary reflector 104.

Advantageously, the inflatable components provide low cost and lowweight. For example, the inflatable components can reduce the loadrequirements to support the dual-surface reflector 100, such as on aroof, for example. Also, the inflatable components can be transportedmore efficiently (due to the low cost and ability to deflate) and storedwhen not in use (in inclement weather, for example).

In another exemplary embodiment, the primary reflector 104, the supportmember 114, the outer perimeter support ring 110, the transparent andflexible material 112, etc. could be constructed through rigid materialswhich maintain shape. In this configuration, the components 136, 138,140 are not required. The microcontroller 142 could be used in thisconfiguration for control of the tracking mechanism 118 and generaloperations of the dual-surface reflector 100.

In both exemplary embodiments of the dual-surface reflector 100, themicrocontroller 142 can include an external interface, such as through anetwork connection or direct connection, to enable user control of thedual-surface reflector 100. For example, the microcontroller 142 caninclude a user interface (UI) to enable custom settings.

The primary reflector 104 can be made from a flexible material such as apolymer (FEP) that is metalized with a thin, highly reflective metallayer that can be followed by additional coatings that protect andcreate high reflectance in the infrared region. Some of the metals thatcan be used for depositing a thin reflector layer on the polymersubstrate material of the inflatable collector can include gold,aluminum, silver, or dielectric materials. Preferably, the surface ofthe primary reflector 104 is metalized and coated such that it isprotected from contamination, scratching, weather, or other potentiallydamaging elements.

The secondary reflector 106 surface can be made in the same manner asthe primary reflector 104 with the reflecting metal layer beingdeposited onto the inside surface of the secondary reflector 106. Forimproved performance, the secondary reflector 106 can be made out of arigid material with a high precision reflective surface shape. In thiscase the, the secondary reflector can be directly attached to thetransparent and flexible material 112 or be sealed to it (impermeable toair) around the perimeter of the secondary reflector 106. Both theprimary reflector 104 and the secondary reflector 106 can utilizetechniques to increase surface reflectivity (such as multi-layers) toalmost 100%.

The dual-surface reflector 100 operates by receiving the solar energy102 through solar radiation through the transparent and flexiblematerial 112, the solar radiation reflects from the primary reflector104 onto the secondary reflector 106 which collimates or slightlyfocuses the solar radiation towards the opening 108. One or more engines(described in FIG. 5) can be located at the opening 108 to receive theconcentrated solar radiation (i.e., using the optical switch 126 and thereflectors 128 to enable multiple engines). The collimated or focusedsolar radiation from the secondary reflector 106 enters throughoptically transparent window on the engines towards a hot end (solarenergy absorber) of a thermodynamic engine.

Advantageously, the dual-surface reflector 100 focuses the solar energy102 and directs it into each of the motors and electric generators 122,124 for their individual heating cycles in a manner that avoids heatingengine components other than the solar energy absorber element in theheating chamber of the motors and electric generators 122, 124.Specifically, the opening 108 extends to the optical switch 126 whichdirects the concentrated solar energy directly into each of the motorsand electric generators 122, 124 through a transparent window of theheating chamber. The materials forming the opening 108 and thetransparent window include materials with absorption substantially closeto zero for infrared radiation.

The dual-surface reflector 100 includes a large volume, and ispreferably suitable for open spaces. For example, the dual-surfacereflector 100 could be utilized in open-space solar farms for powerplants, farms, etc. In an exemplary embodiment, the dual-surfacereflector 100 could be four to six meters in diameter. Alternatively,the dual-surface reflector 100 could be a reduced size for individualhome-use. Advantageously, the light weight of the inflatable componentscould enable use of the dual-surface reflector 100 on a roof. Forexample, a home-based dual-surface reflector 100 could be 0.1 to onemeters in diameter. Also, the reduced cost could enable the use of thedual-surface reflector 100 as a backup generator, for example.

Referring to FIG. 2, multiple solar collectors 200 are illustrated forproviding a flatter and compact arrangement, i.e. a low-profile design,according to an exemplary embodiment of the present invention. FIG. 2illustrates a top view and a side view of the multiple solar collectors200. In the top view, the multiple solar collectors 200 can be arrangedside-by-side along an x- and y-axis. Each of the solar collectors 200includes a focusing/collimating element 202 which is configured toconcentrate solar radiation 102 into a corresponding light guide 204.The focusing/collimating element 202 is illustrated in FIG. 2 with anexemplary profile, and additional exemplary profile shapes areillustrated in FIG. 4.

The focusing/collimating element 202 focuses the solar radiation 102into a cone of light with a numerical aperture smaller than thenumerical aperture of the light guide 204. The focusing/collimatingelement 202 can be made out of a material transparent to infrared solarradiation, such as FEP. The focusing/collimating element 202 can be asolid material or hollow with a flexible skin that allows the element202 to be formed by inflating it with a gas. Forming the element thoughinflation provides weight and material costs advantages.

The light guides 204 can be constructed out of a material that isoptically transparent in the infrared region, such as FEP, glass, orother fluorinated polymers in the Teflon® family, or the light guides204 can be made out of a thin tube (e.g., FEP) filled with a fluid, suchas Germanium tetrachloride or Carbon tetrachloride, that is transparentto infrared radiation. Advantageously, the light guides 204 include amaterial selected so that it has close to zero absorption in thewavelengths of the solar energy 102. The tube material must have ahigher index of refraction than the fluid inside it in order to create astep index light guide that allows propagation of the concentrated solarradiation. The array of the multiple solar collectors 200 can extend inthe X and Y direction as needed to collect more solar energy.

The focusing/collimating element 202, the light guide 204 and theinterface 206 can be rotatably attached to a solar tracking mechanism(not shown). The tracking mechanism is configured to ensure thefocusing/collimating element 202 continuously points toward the sun. Amicrocontroller (not shown) similar to the microcontroller 142 in FIG. 1can control the tracking mechanism along with other functions of themultiple solar collectors 200. The tracking mechanism can individuallypoint each of the focusing/collimating elements 202 towards the Sun, oralternatively, a group tracking mechanism (not shown) can align a groupof elements 202 together.

Referring to FIG. 3, a mechanism 300 is illustrated for combining solarradiation 102 from the multiple light guides 204 in FIG. 2 according toan exemplary embodiment of the present invention. The multiple lightguides 204 are configured to receive concentrated solar radiation fromthe focusing/collimating elements 202 and to guide it and release itinside a hot end of multiple engines and/or generators. Optical couplers302 can be utilized to combine multiple light guides 204 into a singleoutput 304. For example, FIG. 3 illustrates four total light guides 204combined into a single output 306 through a total of three cascadedoptical couplers 302. Those of ordinary skill in the art will recognizethat various configurations of optical couplers 302 can be utilized tocombine an arbitrary number of light guides 204. The optical couplers204 which are deployed in a tree configuration in FIG. 3 reduce thenumber of light 204 guides reaching the engines and/or generators.Alternatively, each light guide 204 could be directed separately intothe engines and/or generators.

An optical splitter 308 and an optical switch 310 can also be includedin the optical path (illustrated connected to a light guide 312 whichincludes a combination of all of the light guides 204) at an optimumlocation along each light guide 204 leading to the engines and/orgenerators. The optical splitter 308 and optical switch 310 permitpulsation of the concentrated solar energy into one or morepiezoelectric generators. Each branch (e.g., two or more branches) ofthe optical splitter 308 leads to a different engine or generator. Theoptical switch 310 sequentially directs the concentrated solar energytraveling along the light guide 312 into different arms of the opticalsplitter 308. For example, the engines and/or generators can includeoffset heating cycles with the optical splitter 308 and the opticalswitch 310 directing solar energy 102 into each engine/generator at itscorresponding heating cycle. Advantageously, this improves efficiencyensuring that collected solar energy 102 is not wasted (as would occurif there was a single engine because the single engine only requires theenergy during the heating cycle).

The optical switch 310 can be integrated into the optical splitter 308as indicated in FIG. 3 or it can exist independently in which case theoptical splitter 308 could be eliminated and the optical switch 310 canhave the configuration presented in FIG. 1 (i.e., optical switch 126 andreflecting surfaces 128). In the case where the optical switch 310 isindependent of the light guide 312, the light guide termination isdesigned to collimate the light directed towards the optical switch 310.The selection of the optimum points where the optical splitters 308 areinserted depends on the power handling ability of the optical switch 310and on economic factors. For example, if the optical switch 310 isinserted in the optical path closer to the engines and/or generators,then fewer switches 310 and shorter light guides 204 are needed, but theoptical switches 310 need to be able to handle higher light intensities.

Referring to FIG. 4, various designs are illustrated for thefocusing/collimating element 202 a-202 e according to an exemplaryembodiment of the present invention. The focusing/collimating element202 a, 202 b, 202 c each include an optically transparent solid material402 shaped in either a bi-convex (element 202 a), a plano-convex(element 202 b), and a meniscus form (element 202 c), all of which havethe purpose to focus the incoming solar energy 102. Additionally, eachof the elements 202 a, 202 b, 202 c also include a flexible “skin”material 404 that together with the optically transparent solid material402 form an inflatable structure 406 which can be inflated with air or adifferent gas. The air/gas pressure in the inflatable structure 406 canbe dynamically controlled to maintain an optimum focal distance betweenthe solid material 402 and the engines and/or generators. The opticallytransparent solid material 402 and the flexible “skin” material 404 aremade out of a material transparent to visible and infrared solarradiation, such as FEP, for example. The focusing/collimating element202 d is a solid convex focusing element constructed entirely of theoptically transparent solid material 402.

The focusing/collimating element 202 e includes an inflatable dualreflector including a primary reflecting surface 408 and a smallersecondary reflecting surface 410 inside an inflatable structure 406. Theprimary reflecting surface 408 and the secondary reflecting surface 410are configured to collectively concentrate the solar radiation 102 intoan opening 412 that leads to the light guide 204. Both reflectingsurfaces 408, 410 can be rigid or flexible such as metalized films oronly the secondary reflector 410 can be made out of a rigid materialwith a high precision reflective surface shape. In this case, thesecondary reflector 410 can be directly attached to the transparentmaterial 404 or can be sealed to it (impermeable to air) around theperimeter of the secondary reflector 410. Some of the metals that can beused for metalizing a thin reflector layer on the polymer substratematerial of the inflatable collector can include gold, aluminum, silver,or dielectric materials. The preferred surface to be metalized is theinside of the inflatable solar collector such that it is protected fromcontamination, scratching, weather, or other potentially damagingelements.

Techniques to increase surface reflectivity (such as multi layerdielectric coatings) to almost 100% can be utilized. Again, the air/gaspressure can be dynamically controlled, based on feedback from pressuresensors monitoring the inside pressure of the inflatable focusingelement, to maintain the optimum focal distance. All transparentmaterials through which solar radiation and concentrated solar radiationpasses through can have their surfaces covered with broad bandanti-reflective coatings in order to maximize light transmission. Thedesigns of the focusing elements 202 presented in FIG. 3 are forillustration purposes and those of ordinary skill in the art willrecognize other designs are possible that would meet the purpose andfunctionality of the focusing elements 202.

The multiple solar collectors 200 can be utilized in buildings, such asoffice buildings, homes, etc. For example, multiple focusing/collimatingelements 202 can be placed on a roof with the light guides 204 extendinginto the building towards a service area, basement, etc. to the enginesand/or generators. Additionally, the light guides 204 heat up verylittle based upon their material construction. Advantageously, the lowprofile design of the solar collectors 200 enables roof placement andthe light guides enable a separate engine location within a building.

Referring to FIGS. 5A and 5B, a partial cross-sectional view illustratesa piezoelectric generator 500 according to an exemplary embodiment ofthe present invention. FIG. 5A illustrates an exemplary embodiment whereconcentrated solar energy 102 travels through free space to enter thegenerator 500 through an optically transparent window 502. Also,multiple optically transparent windows 502 could be utilized. Theoptically transparent window 502 is made out of a material transparentto infrared radiation, such as sapphire, fused silica or the like. Theshape of the optically transparent window 502 is such that itfacilitates sealing of working fluid inside the generator 500 andreduction of back reflection. FIG. 5A shows a trapezoidal cross sectionof the optically transparent window 502 as an exemplary embodiment. Theoptically transparent window 502 can be disposed at an end of theopening 108 or placed adjacent to the reflecting surfaces 128 of thedual-surface reflector 100 in FIG. 1.

FIG. 5B illustrates an exemplary embodiment where concentrated solarradiation enters the generator 500 through a plurality of light guides504. Each of the light guides 504 includes a termination 506 that ismade out of material transparent to infrared radiation and that is alsoresistant to the high temperatures inside the generator 500. The shapeof termination 506 facilitates sealing of working fluid inside thegenerator 506. FIG. 5B shows a trapezoidal cross section of thetermination 506. The termination 506 has an angled tip inside thegenerator 500 that minimizes back reflection inside the light guide 504and also minimizes coupling back into the light guide 506 of radiationfrom the generator 500. The termination 506 includes a very hardmaterial with good optical properties able to withstand hightemperatures. The plurality of light guides 504 can connect to the solarcollectors 200 in FIGS. 2-4. Additionally, the generator 500 can includefewer light guides 504 than solar collectors 200 utilizing the mechanism300 in FIG. 3 to combine light guides 204.

In both FIGS. 5A and 5B, the optically transparent window 502 and theplurality of light guides 504 transfer concentrated solar energydirectly into a heat chamber 508 of the generator 500. Advantageously,this direct transfer provides a lower temperature of the generator 500and reduced thermal stress on a generator body 510 of the generator 500.This leads to longer generator 500 life, better reliability, increasedefficiency, and the like.

Additionally, the optically transparent window 502 and the plurality oflight guides 504 can be configured to transfer the solar energy in apulsating manner. The pulsating manner means that the solar energy isallowed to enter into the chamber 508 of the generator 500 periodically,for a predetermined period of time, similar to turning a switch ON andOFF. During the OFF period for a particular generator 500, the solarenergy is directed into a second, or third, or other generator 500 in arotating, periodical fashion. In this way, all the energy from thecollector is utilized. Also, during the OFF period for a particulargenerator 500, heat is removed from working fluid 510 as part of thethermodynamic cycle. An advantage of pulsating the energy is that solarenergy is added to the working fluid 510 in a controlled manner only atthe desired time.

Transferring the concentrated solar energy directly into the heatchamber 508 of the generator 500 provides great benefits. The generatorbody 510 has a lower temperature and the thermal stress and thermalaging in the body 510 is reduced. The chamber 508 can be surrounded byheat removing elements 512 such as any type of heat exchanger. The heatexchanger can actually be located inside the chamber 508 to maximize therate of heat transfer and prevent the walls of the generator 500 fromheating up excessively. In an exemplary embodiment, the heat removingelements 512 can include tubes with circulating water being used toremove heat. The heat extracted into the cooling water can be dissipatedinto the air through another heat exchanger or can be used as a heatsource for heating, for example, household water.

Advantageously, inserting the solar energy directly into the workingfluid 510 in a pulsating manner can improve the efficiency of thegenerator 500 because the outside temperature of the hot end of thegenerator 500 can be greatly reduced and therefore the radiated heatloss is decreased. The working fluid 510 can be a gas, typicallypressurized, steam, a phase change material, or any other working fluidutilized in closed-cycle thermodynamic engines. The working fluid 510can include an energy absorbing material that is designed to have alarge surface area and is made out of a material that absorbs infraredradiation and that can efficiently release it to the working fluid. Suchmaterials include graphite or other type of carbon based material, asuitable metal, or a metal oxide. The energy absorber can be alsoinclude carbon nano particles or other nano size particles uniformlydistributed and suspended in the working fluid 510.

A bottom portion 514 of the generator 500 and the heat chamber 510 areattached in a sealed manner through a flexible bellow section 516 thatallows the bottom portion 514 to move when the pressure in the heatchamber 510 increases. As a result, the stacks of piezoelectric elements518 are compressed and a voltage is generated. The piezoelectricelements 518 can be connected in series or parallel (or combination ofseries and parallel) to generate the desired voltage and current. Theelectrical energy can be distributed for use or stored for future use.

The generator 500 is shown for illustration purposes. Those of ordinaryskill in the art will recognize that the dual-surface reflector 100 andthe multiple solar collectors 200 can be utilized to concentrate anddirectly deliver solar energy into any type of generator.

Advantageously, the designs described herein enable distributedelectrical energy generation from a few kWs to 10's of kW per unit at alow cost. The present invention can directly generate AlternatingCurrent (AC) electricity without a need for inverters. Also, the presentinvention can provide heat output which can be used, for example, forspace heating, water heating, air conditioning, micro desalinationplants, and the like. The present invention provides low installationcosts and low overall maintenance costs. Additionally, the presentinvention can enable a modular design, such as adding additional solarcollectors as needed to scale energy generation.

Referring to FIGS. 6A and 6B, a partial cross-sectional view illustratesa closed-cycle thermodynamic based engine 600 according to an exemplaryembodiment of the present invention. FIG. 6A illustrates an exemplaryembodiment where concentrated solar energy 102 travels through freespace to enter the engine 600 through an optically transparent window602. Also, multiple optically transparent windows 602 could be utilized.The optically transparent window 602 is made out of a materialtransparent to infrared radiation, such as sapphire, fused silica or thelike. The shape of the optically transparent window 602 is such that itfacilitates sealing of working fluid inside the engine 600 and reductionof back reflection. FIG. 6A shows a trapezoidal cross section of theoptically transparent window 602 as an exemplary embodiment. Theoptically transparent window 602 can be disposed at an end of theopening 108 or placed adjacent to the reflecting surfaces 128 of thedual-surface reflector 100 in FIG. 1.

FIG. 6B illustrates an exemplary embodiment where concentrated solarradiation enters the engine 600 through a plurality of light guides 604.Each of the light guides 604 includes a termination 606 that is made outof material transparent to infrared radiation and that is also resistantto the high temperatures inside the engine 600. The shape of termination606 facilitates sealing of working fluid inside the engine 606. FIG. 6Bshows a trapezoidal cross section of the termination 606. Thetermination 606 has an angled tip inside the engine 600 that minimizesback reflection inside the light guide 604 and also minimizes couplingback into the light guide 606 of radiation from the engine 600. Thetermination 606 includes a very hard material with good opticalproperties able to withstand high temperatures. The plurality of lightguides 604 can connect to the solar collectors 200 in FIGS. 2-4.Additionally, the engine can include fewer light guides 604 than solarcollectors 200 utilizing the mechanism 300 in FIG. 3 to combine lightguides 204.

The engine 600 can include a Stirling-type engine, a Rankine-typeengine, or the like. A Stirling engine is a closed-cycle regenerativeheat engine with a gaseous working fluid. The Stirling engine isclosed-cycle because the working fluid, i.e., the gas in a heat chamber608 which pushes on a piston 610, is permanently contained within theengine 600. This also categorizes it as an external heat engine whichmeans it can be driven by any convenient source of heat. “Regenerative”refers to the use of an internal heat exchanger called a ‘regenerator’which increases the engine's thermal efficiency compared to the similarbut simpler hot air engine.

In both FIGS. 6A and 6B, the optically transparent window 602 and theplurality of light guides 604 transfer concentrated solar energydirectly into the heat chamber 608 of the engine 600. Advantageously,this direct transfer provides a lower temperature of the engine 600 andreduced thermal stress on a body 612 of the engine 600. The engine 600can include a liner 614 made out of a material that is a reflector ofinfrared radiation and at the same time has poor thermal conductivity(thermal insulator). Advantageously, the liner 614 keeps heat inside theengine 600 avoiding excessive heating of the engine body. This leads tolonger engine life, better reliability, increased efficiency, and thelike.

The heat chamber 608 is delimited at one end by the piston 610 whichmoves in a reciprocating manner inside the engine 600. The efficiency ofthe engine 600 is improved in the present invention because the outsidetemperature of the hot end of the engine 600 is greatly reduced(compared to conventional designs) and therefore the radiated heat lossis decreased. Inside the heat chamber 608, the concentrated solarradiation is absorbed and the energy heats up the working fluid in thechamber. The working fluid can be a gas (typically pressurized), steam,a phase change material, or any other working fluid utilized inclosed-cycle thermodynamic engines. The optically transparent window 602can be shaped in a trapezoidal shape or the like to seal the heatchamber 608, i.e. through the pressurized gas. Alternatively, seals canbe located on the optically transparent window 602 or around theplurality of light guides 604.

The heat chamber 608 includes an energy absorber and gas heater 616which is designed to have a large surface area. The energy absorber andgas heater 616 is made out of a material that absorbs infrared radiationand can efficiently release it to the working fluid such as graphite orother type of carbon-based material, a suitable metal, a metal oxide, orthe like. The energy absorber and gas heater 616 can include carbon nanoparticles or other nano size particles uniformly distributed andsuspended in the working fluid.

The engine 600 also includes one or more heat exchangers for cooling thegas inside the heat chamber 608 at an appropriate time during thethermodynamic cycle. One or more linear generators or the like (notshown) can be coupled to a rod 618 of the pistons 610. Generally, thegenerators are configured to convert mechanical energy from the pistons610 into electrical energy. The electrical energy can be distributed foruse or stored for future use.

The engine 600 is shown for illustration purposes. Those of ordinaryskill in the art will recognize that the dual-surface reflector 100 andthe multiple solar collectors 200 can be utilized to concentrate anddirectly deliver solar energy into any type of engine. Of note, thepresent invention delivers concentrated solar energy directly into theheat chamber 608 to avoid heating the engine body.

Advantageously, the designs described herein enable distributedelectrical energy generation from a few kWs to 10's of kW per unit at alow cost. The present invention can directly generate AlternatingCurrent (AC) electricity without a need for inverters. Also, the presentinvention can provide heat output which can be used, for example, forspace heating, water heating, air conditioning, micro desalinationplants, and the like. The present invention provides low installationcosts and low overall maintenance costs. Additionally, the presentinvention can enable a modular design, such as adding additional solarcollectors as needed to scale energy generation.

Referring to FIG. 7, an energy distribution and delivery system 700 isillustrated for concentrated solar energy that allows the release of theconcentrated solar energy in a pulsating manner directly into one ormore engines and/or generators according to an exemplary embodiment ofthe present invention. The energy distribution and delivery system 700is illustrated with two exemplary engines/generators 702 a, 702 b, andthose of ordinary skill in the art will recognize the energydistribution and delivery system 700 could use additionalengines/generators 702 or the like.

Each of the engines/generators 702 a, 702 b includes a first heatingchamber 704 a, 704 b and a second heating chamber 706 a, 706 b. Theenergy distribution and delivery system 700 is configured to maximizeusage of collected solar energy 102 by distributing the solar energy 102to each heating chamber 704 a, 704 b, 706 a, 706 b at appropriate timesin their respective cycles. For example, the solar energy 102 can becollected utilizing the dual-surface reflector 100 and/or the multiplesolar collectors 200 described herein.

The energy distribution and delivery system 700 includes multiplereflective disks 710, 712, 714, 716 for distributing the collected solarenergy 102. Note, these reflective disks 710, 712, 714, 716 could beincluded within a light guide, for example. Additionally, the opticalswitch and splitter described herein could provide similar functionalityto the reflective disks 710, 712, 714, 716. The reflective disks 710,712, 714, 716 are configured to either reflect or pass through thecollected solar energy 102. Additionally, each of the reflective disks710, 712, 714, 716 is configured to rotate to either reflect or passthrough the collected solar energy 102.

FIG. 7 illustrates an exemplary operation of the energy distribution anddelivery system 700. The collected solar energy 102, during a timeperiod 720 (following a dashed line A), passes through an opening of thefirst disk 710 and enters the heating chamber 704 a of theengine/generator 702 a. During a time period 722 (following a dashedline B), the concentrated solar energy 102 is reflected off the firstdisk 710, passes through the second disk 712, and reflects off the thirddisk 716 to enter the heating chamber 704 b of the engine/generator 702b.

During a time period 724 (following a dashed line C), the concentratedsolar energy 102 reflects off the first disk 710, reflects off thesecond disk 712, and reflects off reflectors 730, 732 to enter theheating chamber 706 a of the engine/generator 702 a. The reflectors 730,732 are positioned to direct the concentrated solar energy 102, andlight guides could also be utilized. During a time period 734 (followinga dashed line D), the concentrated solar energy 102 reflects off thefirst disk 710, passes through the second disk 712 and the third disk714, and reflects off the fourth disk 716 and reflective surfaces 740,742 to enter the heating chamber 706 b of the engine/generator 702 b.

The cycle can then start all over again. The energy distribution anddelivery system 700 can be used for one, two, or more generator chainedin a similar fashion. The size and shape of the reflecting surfaces oneach individual disk can be tailored for obtaining optimum performance.For example, the duration of the energy input in any chamber 704 a, 704b, 706 a, 706 b can be adjusted by varying the size of the reflectingsurface (or a combination of multiple reflecting surfaces) and therotational speed of the disk 710, 712, 714, 716. The energy distributionand delivery system 700 can include motors (not shown) configured torotate the disks 710, 712, 714, 716. The pulsating manner of energytransfer allows the solar energy to enter into the chamber of thegenerator periodically, for a controllable period of time, similar toturning a switch ON and OFF. Also, the energy distribution and deliverysystem 600 can utilize the optical splitter 308 and the optical switch310 in a similar fashion as the reflective disks 710, 712, 714, 716 todistribute the solar energy 102.

Referring to FIGS. 8 and 9, a solar array 800 is illustrated in aschematic top and cross-sectional view according to an exemplaryembodiment of the present invention. As illustrated in the top view, thesolar array 800 includes a plurality of solar collectors 200 such asdescribed herein. The present invention utilizes various distributionmechanisms to distribute collected solar energy from the solarcollectors 200 to multiple engines/generators. Specifically, thesemechanisms enable more engine/generators than corresponding solarcollectors 200. Advantageously, the solar array 800 utilizes thesedistribution mechanisms to more efficiently use collected solar energy.

The solar array 800 includes multiple generators 500 (FIG. 8) or engines600 (FIG. 9). Those of ordinary skill in the art will recognize that thesolar array 800 can be utilized with any device adapted to receiveconcentrated solar radiation. The solar array 800 directs concentratedsolar energy through free space to enter the generator 500 or engine 600through an optically transparent window 502, 602.

In the examples of FIGS. 8 and 9, the solar array 800 includes foursolar collectors 200 with each solar collector 200 providingconcentrated solar energy to two generators/engines 500, 600. Each solarcollector 200 directs concentrated solar energy in free space to anoptical switch 802. The optical switch 802 is configured to direct theconcentrated solar energy to a reflective surface 804. The opticalswitch 802 can include oscillating (vibrating) reflective surface orsurfaces (such as MEMS), or a refractive switch. The reflective surfaces804 can be fixed with a flat or curved surface (such that to minimizethe loss of solar energy during the transient part of the switch 802movement) or can move in sync with the optical switch 802 in such a wayto minimize the loss of solar energy during the transient part of theswitch movement. Other designs, such as based on refractive opticalelements, are possible that distribute the light to the desiredlocations. In this example, there are two reflective surfaces 804, onefor each generator/engine 500, 600. The present invention contemplatesadditional reflective surfaces 804 as required for additionalgenerators/engines 500, 600.

Both the optical switch 802 and the reflective surfaces 804 areconfigured to rotate to enable concentrated solar energy to betransferred in a pulsating manner directly into the working fluid insidethe chamber of the generator/engine 500, 600. The pulsating manner ofenergy transfer means that the solar energy is allowed to enter into thechamber of the generator/engine 500, 600 periodically, for apredetermined period of time, similar to turning a switch ON and OFF.When a particular engine 600 or generator 500 is in the OFF period, thesolar energy is directed into the next engine 600 or generator 500 (ofthe same solar collector 200) and so on in a cyclical fashion. In thisway, almost all the energy from the solar collector 200 is utilized.

Clearly, multiple (more than three) closed-cycle thermodynamic engines600 and piezo-electric generators 500 can be made to belong to the samesolar array 800 and correspond to the same solar collector 200. Forexample in FIG. 8, an output 810 of the generators 600 from multiplecells can be connected in series, in parallel, or a combination ofseries and parallel connections in order to optimize the desired overalloutput. The output 810 of the generators 600 can also be connected inconfigurations that result in single phase, two phases, or three phasesoverall outputs. The output 810 is connected to plates at the end ofpiezo-electric stacks 812. The cyclical distribution of solar energyinto multiple engine-generator combination can be made to match thedesired number of output phases. Multiple phase outputs can be generatedeither from phase shifting outputs from multiple groups of cells, or byhaving multiple phases coming out of each cell (from multiplegenerators).

During the OFF period of a particular generator/engine 500, 600, heat820 is removed from the working fluid of that generator/engine 500, 600as part of the thermodynamic cycle, such as the heat exchange mechanismsdescribed herein in FIGS. 5 and 6. An advantage of pulsating the energyis that solar energy is added to the working fluid in a controlledmanner only at the desired time and for the desired duration. That alsoallows for a dynamic control scheme of the output power (switches canreconfigure the connection among the outputs from individualgenerators/engines 500, 600) for cases when solar energy varies (such asdue to clouds). In this way, the output power can change while thevoltage and the AC current frequency can stay essentially constant.

Referring to FIGS. 10 and 11, a solar array 1000 is illustrated in aschematic cross-sectional view according to an exemplary embodiment ofthe present invention. The solar array 1000 includes a dual-surfacereflector 100 or the like configured to collect and concentrate solarenergy. The solar array 1000 utilizes similar distribution mechanisms asdescribed in FIGS. 8 and 9 to distribute collected solar energy from thedual-surface reflector 100 to multiple generators/engines 500, 600thereby enabling more efficient use of collected solar energy.Specifically, these mechanisms enable multiple engine/generators 500,600 for the corresponding dual-surface reflector 100. Advantageously,the solar array 1000 utilizes these distribution mechanisms to moreefficiently use collected solar energy. FIG. 10 illustrates the solararray 1000 with multiple piezoelectric generators 500, and FIG. 11illustrates the solar array 1000 with multiple closed-cyclethermodynamic based engines 600.

Referring to FIGS. 12-15, solar arrays 1200, 1400 are illustrated invarious schematic views according to an exemplary embodiment of thepresent invention. Each of the solar arrays 1200, 1400 utilize lightguides 504, 604 with terminations 506, 606 directly in heating chambersof the generators 500 and engines 600. The light guides 504, 604 areused to direct the collected solar energy in lieu of free spacetransmission with optical switches and reflective surfaces.Specifically, the solar arrays 1200, 1400 utilize the distributionmechanism 300 described herein in FIG. 3.

FIG. 12 illustrates the solar array 1200 with multiple piezo-electricgenerators 500 adapted to receive collected solar energy from multiplesolar collectors 200. In this example, there are two generators 500 foreach solar collector 200. Accordingly, the light guide 504 includes asingle switch 310 operable to split the light guide 504 into twodirections into separate terminations 506 in each generator 500. Thoseof ordinary skill in the art will recognize that each solar collector200 could serve more than two generators 500 with the addition ofsplitters and optical switches. FIG. 13 illustrates the solar array 1200with multiple closed-cycle thermodynamic engines 600 in a similarconfiguration.

FIG. 14 illustrates the solar array 1400 with multiple piezo-electricgenerators 500 adapted to receive collected solar energy from adual-surface reflector 100. In this example, there are three generators500 for the single dual-surface reflector 100. Accordingly, the lightguide 504 includes two optical switches 310, i.e. two switches enabletwo branches in the light guides 504 to allow a total of threeterminations 506. Thus, the solar array 1400 provides three generators500 for one dual-surface reflector 100. The present inventioncontemplates additional generators 500 with more splitters and opticalswitches. FIG. 15 illustrates the solar array 1400 with multipleclosed-cycle thermodynamic engines 600 in a similar configuration.

Referring to FIG. 16, a flowchart illustrates an energy distribution anddelivery mechanism 1600 for concentrating and releasing solar energy ina pulsating manner directly into multiple systems according to anexemplary embodiment of the present invention. As described herein, eachsystem can include a piezo-electric generator, a closed-cyclethermodynamic engine, or the like. The distribution and deliverymechanism 1600 collects solar energy (step 1602). The collection stepcan include the mechanisms described herein with respect to thedual-surface reflector 100 and/or the multiple solar collectors 200.

Next, the distribution and delivery mechanism 1600 directs the collectedsolar energy to a first heat chamber in a first system for apredetermined time period (step 1604). The predetermined time period cancorrespond to a heating cycle for the first system. After thepredetermined time period, the collected solar energy is directed to anext first heat chamber in a next system for another predetermined timeperiod (step 1606).

The distribution and delivery mechanism 1600 checks if there is anothersystem (step 1608). Here, the distribution and delivery mechanism 1600is configured to cycle through all of the system to provide collectedsolar energy into the associated first heat chambers of each system. Ifthere is another system, the distribution and delivery mechanism 1600returns to step 1606.

If not, the distribution and delivery mechanism 1600 directs thecollected solar energy to a second heat chamber in the first system fora predetermined time period (step 1610). Then, the distribution anddelivery mechanism 1600 directs the collected solar energy to a nextsecond heat chamber in the next system for a predetermined time period(step 1612).

The distribution and delivery mechanism 1600 checks if there is anothersystem (step 1614). Here, the distribution and delivery mechanism 1600is configured to cycle through all of the systems to provide collectedsolar energy into the associated second heat chambers of each system. Ifthere is another system, the distribution and delivery mechanism 1600returns to step 1616. If not, the distribution and delivery mechanism1600 can return to step 1604 for another cycle through each of the heatchambers.

Referring to FIG. 17, a flow chart illustrates a mechanism 1700 toconvert solar energy into electric energy according to an exemplaryembodiment of the present invention. The mechanism 1700 includes:continuously positioning one or more solar collectors towards the sun(step 1702); collecting solar radiation at each of the one or more solarcollectors (step 1704); directing the collected solar radiation to aheat chamber in a generator or an engine (step 1706); periodically andcontrollably heating a working fluid in the generator with the directedsolar radiation (step 1708); reciprocating a piezoelectric generator ora closed-cycle thermodynamic engine responsive to pressure changes inthe working fluid (step 1710); collecting the generated electricalenergy (step 1712); cooling the working fluid (step 1714), and repeatingthe mechanism 1700.

Referring to FIG. 18, a block diagram illustrates a controller 1800 forcontrolling the pulsating manner of solar energy distribution accordingto an exemplary embodiment of the present invention. The controller 1800can be a digital computer that, in terms of hardware architecture,generally includes a processor 1802, input/output (I/O) interfaces 1804,network interfaces 1806, a data store 1808, and memory 1810. Thecomponents (1802, 1804, 1806, 1808, and 1810) are communicativelycoupled via a local interface 1812. The local interface 1812 can be, forexample but not limited to, one or more buses or other wired or wirelessconnections, as is known in the art. The local interface 1812 can haveadditional elements, which are omitted for simplicity, such ascontrollers, buffers (caches), drivers, repeaters, and receivers, amongmany others, to enable communications. Further, the local interface 1812can include address, control, and/or data connections to enableappropriate communications among the aforementioned components.

The processor 1802 is a hardware device for executing softwareinstructions. The processor 1802 can be any custom made or commerciallyavailable processor, a central processing unit (CPU), an auxiliaryprocessor among several processors associated with the controller 1800,a semiconductor-based microprocessor (in the form of a microchip or chipset), or generally any device for executing software instructions. Whenthe controller 1800 is in operation, the processor 1802 is configured toexecute software stored within the memory 1810, to communicate data toand from the memory 1810, and to generally control operations of thecontroller 1800 pursuant to the software instructions.

The I/O interfaces 1804 can be used to receive user input from and/orfor providing system output to one or more devices or components. Userinput can be provided via, for example, a keyboard and/or a mouse.System output can be provided via a display device and a printer (notshown). I/O interfaces 1804 can include, for example, a serial port, aparallel port, a small computer system interface (SCSI), an infrared(IR) interface, a radio frequency (RF) interface, and/or a universalserial bus (USB) interface.

The network interfaces 1806 can be used to enable the controller 1800 tocommunicate on a network, such as to a client or the like. The networkinterfaces 1806 can include, for example, an Ethernet card (e.g.,10BaseT, Fast Ethernet, Gigabit Ethernet) or a wireless local areanetwork (WLAN) card (e.g., 802.11a/b/g/n). The network interfaces 8106can include address, control, and/or data connections to enableappropriate communications on the network.

A data store 1808 can be used to store data, such as configuration dataand the like. The data store 1808 can include any of volatile memoryelements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM,and the like)), nonvolatile memory elements (e.g., ROM, hard drive,tape, CDROM, and the like), and combinations thereof. Moreover, the datastore 1808 can incorporate electronic, magnetic, optical, and/or othertypes of storage media. In one example, the data store 1808 can belocated internal to the controller 1800 such as, for example, aninternal hard drive connected to the local interface 1812 in thecontroller 1800.

The memory 1810 can include any of volatile memory elements (e.g.,random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)),nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, etc.),and combinations thereof. Moreover, the memory 1810 may incorporateelectronic, magnetic, optical, and/or other types of storage media. Notethat the memory 1810 can have a distributed architecture, where variouscomponents are situated remotely from one another, but can be accessedby the processor 1802.

The software in memory 1810 can include one or more software programs,each of which includes an ordered listing of executable instructions forimplementing logical functions. In the example of FIG. 18, the softwarein the memory system 1810 includes a suitable operating system (O/S)1840 and a pulsation control program 1842. The operating system 1840essentially controls the execution of other computer programs, such asthe pulsation control program 1842, and provides scheduling,input-output control, file and data management, memory management, andcommunication control and related services. The operating system 1840can be any of Windows NT, Windows 2000, Windows XP, Windows Vista (allavailable from Microsoft, Corp. of Redmond, Wash.), Solaris (availablefrom Sun Microsystems, Inc. of Palo Alto, Calif.), LINUX (or anotherUNIX variant) (available from Red Hat of Raleigh, N.C.), or the like.

The pulsation control program 1842 is configured to control the variousdistribution mechanisms described herein to enable distribution ofcollected solar energy from one or more solar collectors to multipleengines/generators in a pulsating manner. Specifically, the controller1800 can be internal or external to the various devices describedherein. The controller 1800 is communicatively coupled, such as throughthe network interface 1806 or I/O interfaces 1804, to the opticalswitches, splitters, reflective surfaces, etc. The pulsation controlprogram 1842 is configured to control these devices to distribute energyas required to the multiple engines/generators. For example, thepulsation control program 1842 can perform the distribution based onpreconfigured settings or based upon adaptive settings using feedback todetermine optimal heating cycle lengths for each engine/generator. Theengines/generators and solar collectors can further include embeddedsensors which report operational data to the controller 1800. Thisoperational data can be utilized in the adaptive settings to provideoptimal energy generation.

Referring to FIGS. 19A and 19B, a closed-cycle thermodynamic engine 1900is illustrated with an integrated electric generator according to anexemplary embodiment of the present invention. FIG. 19A illustrates across-sectional side view and FIG. 19B illustrates an end view. Theclosed-cycle thermodynamic engine 1900 includes a cylinder body 1902with heat chambers 1904, 1906 located at each end of the cylinder body1902. Concentrated solar energy 1908 enters in an alternating orpulsating manner into the two heat chambers 1904, 1906 through theoptically transparent ends 1910. For example, the optically transparentends 1910 can include sapphire, fused silica, or other suitablematerial. Alternatively, the concentrated solar energy 1908 can enterthrough one or more light guides as described herein.

The two optically transparent ends 1910 are disposed at opposite ends ofthe cylinder body 1902 thereby forming a sealed cylindrical shape with ahollow interior. The hollow interior includes the two heat chambers1904, 1906 at each end of the body 1902 with a reciprocating piston 1912slidingly disposed with the interior of the hollow body. Each heatchamber 1904, 1906 includes an energy absorber 1914 that is configuredto absorb the concentrated solar energy 1908 and release it into aworking fluid (or gas) inside the heat chambers 1904, 1906. The gas orfluid in the heat chambers 1904, 1906 can be pressurized. For example,the working fluid can be a gas (typically pressurized, such as hydrogen,helium, air, etc.), steam, a phase change material, or any other workingfluid utilized in closed-cycle thermodynamic engines.

The cylinder body 1902 has two flat ends where the concentrated solarenergy enters and is essentially transparent to visible and infra-redradiation. Additionally, the piston 1912 can also be essentiallytransparent to visible and infra-red (IR) radiation. The piston 1912forms a tight fit is inside the hollow interior but it is free to movein a reciprocating manner without friction. For example, lubrication orthe like can be utilized. There are one or more magnets (orelectro-magnets) 1916 disposed to the piston 1912 that together withcoils 1918 disposed to the cylinder body 1902 form a linear electricgenerator. The coils 1918 are static and are illustrated in a recessedarea of the cylinder body 1902. Alternatively, the magnets' 1916diameter can be smaller and the coils 1918 can be placed inside thecylinder body 1902 without the need of a recessed area. Otherembodiments are also contemplated. In an exemplary embodiment, the coils1918 can extend around a circumference of the hollow interior, and themagnets 1916 can extend around a circumference of the piston 1912.

The linear electric generator can be wired to produce single ormulti-phase voltage outputs. The cylinder body 1902 is surrounded, oversubstantially the entire surface, with a heat exchanger 1920. The heatextracted by the heat exchanger 1920 can be dissipated into the air orit can be used as a heat source for heating, for example, householdwater. Also, one or more fiber optic bundles 1924 (FIG. 19B shows fourfiber optic bundles) extend between the two heat chambers 1904, 1906 totransfer solar radiation between the chambers 1904, 1906. The fiberoptic bundles 1924 provide bidirectional transfer of a portion of thehot gas energy between the engine chambers to provide cooling and toreuse energy.

Referring to FIGS. 20A and 20B, a closed-cycle thermodynamic engine 2000is illustrated with an external electric generator according to anexemplary embodiment of the present invention. The closed-cyclethermodynamic engine 2000 includes a similar structure as theclosed-cycle thermodynamic engine 1900. Instead of an internal electricgenerator, the closed-cycle thermodynamic engine 2000 includes anexternal electric generator with a mechanism 2002 that convertsreciprocal motion of the piston 1912 to rotational motion. The mechanism2002 thereby rotates a magnetic disk 2004 insides the cylinder body 1902and the magnetic disk 2004 is magnetically coupled to another magneticdisk 2006 located external to the cylinder body 1902. The magnetic disk2006 is attached to a shaft 2008 that is connected to a rotatingelectric generator 2010 external to the closed-cycle thermodynamicengine 2000.

The closed-cycle thermodynamic engines 1900, 2000 are configured to useany of the solar energy collection and distribution mechanisms describedherein. This includes the pulsating distribution mechanisms describedherein. Additionally, the present invention contemplates multipleclosed-cycle thermodynamic engines 1900, 2000 configured in array.

Referring to FIG. 21, a flowchart illustrates engine operation 2100 ofthe closed-cycle thermodynamic engines 1900, 2000 according to anexemplary embodiment of the present invention. Concentrated solar energyenters a first chamber of a closed-cycle thermodynamic engine for apredetermined time period (step 2102). The concentrated solar energy isabsorbed by an energy absorber and released into a working gas (step2104). The gas heats up expanding to exert force through pressure on apiston (step 2106). The piston reciprocates thereby passing magnetsattached to the piston by coils generating a voltage in the coils (step2108). Alternatively, the piston can include a mechanism to translate areciprocating force to a rotational force to drive an externalgenerator.

While reciprocating, energy from the first chamber passes to a secondchamber or vice versa through the piston's body and through a fiberoptic bundle (step 2110). Also, the gas in the chamber (either the firstor the second chamber) is further cooled by an attached heat exchanger(step 2112). Concentrated solar energy enters the second chamber for apredetermined time period (step 2114). The engine operation 2100continues (back to step 2104) as long as energy is added to eachchamber.

The magnet can include an electro-magnet on the piston which can bemodified in strength to accommodate for variations of the input solarenergy (such as when clouds temporarily block the sun). Collected andconcentrated solar energy can be split among multiple engines to utilizeall the energy as described herein. For example, after energy is allowedinto the first chamber of one engine, the energy can be directed to thefirst chamber of the second engine, and after that to the second chamberof the first engine, and so on.

Although the present invention has been illustrated and described hereinwith reference to preferred embodiments and specific examples thereof,it will be readily apparent to those of ordinary skill in the art thatother embodiments and examples may perform similar functions and/orachieve like results. All such equivalent embodiments and examples arewithin the spirit and scope of the present invention and are intended tobe covered by the following claims.

1. A closed-cycle thermodynamic engine, comprising: an engine body; afirst heat chamber and a second heat chamber at opposite ends of theengine body; a solar collection apparatus connected to the first heatchamber and the second heat chamber and configured to distributecollected solar energy into each of the first heat chamber and thesecond heat chamber for a predetermined time period; a piston slidinglydisposed within the engine body between the first heat chamber and thesecond heat chamber; and an electrical generation device configured togenerate electricity based upon reciprocation of the piston.
 2. Theclosed-cycle thermodynamic engine of claim 1, further comprising: a heatabsorber in each of the first heat chamber and the second heat chamber;wherein the heat absorber operable to absorb the collected solar energyand to release heat into a working fluid in each of the first heatchamber and the second heat chamber.
 3. The closed-cycle thermodynamicengine of claim 1, further comprising: one or more fiber optic linksbetween the first heat chamber and the second heat chamber; wherein theone or more fiber optic links are operable to exchange heat between thefirst heat chamber and the second heat chamber to thereby assist in acooling cycle.
 4. The closed-cycle thermodynamic engine of claim 3,further comprising: a heat exchanger coupled to the engine body; whereinthe heat exchange is operable to cool each of the first heat chamber andthe second heat chamber in the cooling cycle.
 5. The closed-cyclethermodynamic engine of claim 1, wherein the engine body comprises asealed cylindrical shape comprising the first heat chamber and thesecond heat chamber at opposite ends of the sealed cylindrical shape;and wherein the sealed cylindrical shape comprises optically transparentends at opposite ends of the sealed cylindrical shape operable to allowconcentrated solar energy to enter the first heat chamber and the secondheat chamber.
 6. The closed-cycle thermodynamic engine of claim 5,wherein the optically transparent ends and the piston comprise amaterial essentially transparent to visible and infra-red (IR)radiation.
 7. The closed-cycle thermodynamic engine of claim 1, furthercomprising: one or more magnets disposed to the piston; and one or morecoils disposed to an interior of the engine body; wherein reciprocationof the piston thereby causes the one or more magnets to generate avoltage in the one or more coils.
 8. The closed-cycle thermodynamicengine of claim 7, wherein the one or more magnets compriseelectro-magnets comprising variable magnetic strength adjustedresponsive to an amount of collected solar energy.
 9. The closed-cyclethermodynamic engine of claim 1, further comprising: a mechanismdisposed to the piston operable to convert reciprocal motion of thepiston to rotational motion; a shaft disposed to the mechanism; and anexternal electric generator disposed to the shaft.
 10. The closed-cyclethermodynamic engine of claim 1, further comprising: a mechanismdisposed to the piston operable to convert reciprocal motion of thepiston to rotational motion; a interior shaft disposed to the mechanism;an interior magnet disposed to the shaft; an exterior magnet outside ofthe engine body in proximity of the interior magnet and operable torotate responsive to rotation of the interior magnet; and an externalelectric generator disposed to an exterior shaft disposed to theexterior magnet.
 11. The closed-cycle thermodynamic engine of claim 1,further comprising: a pulsation algorithm operable to control the solarcollection apparatus to control the predetermined time period.
 12. Amethod of operating a closed-cycle thermodynamic engine, comprising:distributing collected solar energy in a first chamber for a first timeperiod; reciprocating a piston responsive to expansion of a firstworking fluid in the first chamber; cooling off the first chamber whiledistributing the collected solar energy in a second chamber for a secondtime period; reciprocating the piston responsive to expansion of asecond working fluid in the second chamber; and generating electricalenergy during the reciprocating steps.
 13. The method of operating aclosed-cycle thermodynamic engine of claim 12, further comprising:cooling off the second chamber while distributing the collected solarenergy in the first chamber for the second time period; and repeatingthe method.
 14. The method of operating a closed-cycle thermodynamicengine of claim 12, further comprising: utilizing a heat absorber in thefirst chamber and the second chamber to absorb the collected solarenergy and to release heat into a working fluid in each of the firstchamber and the second chamber.
 15. The method of operating aclosed-cycle thermodynamic engine of claim 12, further comprising:utilizing one or more fiber optic links between the first chamber andthe second chamber to exchange heat between the first chamber and thesecond chamber to thereby assist in a cooling cycle.
 16. The method ofoperating a closed-cycle thermodynamic engine of claim 15, furthercomprising: utilizing a heat exchanger to cool each of the first chamberand the second chamber in the cooling cycle.
 17. The method of operatinga closed-cycle thermodynamic engine of claim 12, further comprising:adjusting an electro-magnetic magnet strength responsive to the amountof collected solar energy.
 18. The method of operating a closed-cyclethermodynamic engine of claim 12, further comprising: adjusting apulsation algorithm to control the first time period and the second timeperiod.
 19. A closed-cycle thermodynamic engine apparatus, comprising:an engine body; a first chamber and a second chamber at opposite ends ofthe engine body; a solar collection apparatus connected to the firstchamber and the second chamber and configured to distribute collectedsolar energy into each of the first chamber and the second chamber for apredetermined time period; a piston slidingly disposed within the enginebody between the first chamber and the second chamber; an electricalgeneration device configured to generate electricity based uponreciprocation of the piston; and a controller coupled to the firstchamber, the second chamber, the solar collection apparatus, and theelectrical generation device, wherein the controller is configured tocontrol pulsation of the collected solar energy into each of the firstchamber and the second chamber.
 20. The closed-cycle thermodynamicengine apparatus of claim 19, wherein the solar collection apparatus iscoupled to the engine body in a manner to avoid excessive heating of theengine body and the piston.